The light sources which were used heretofore may operate in the ultraviolet (UV) region, in the visible light range, or in the near infrared (IR) spectral range. Such light sources may have a substantial extent; they may, for example, have a length of two meters about 63/4 feet or the like and should, throughout their length, have uniform light emission.
It is difficult to make elongated light sources which have uniform light emission throughout their length of such large size. The reject rate of such lamps, in manufacture, is high. Additionally, as the lamps are used and as they age, the light distribution along the length thereof changes unpredictably, leading to warranty claims and complaints, while requiring an excessive amount of maintenance and replacement time.